Honda Motorcycles - FireBlades.org banner

1 - 9 of 9 Posts

·
Registered
Joined
·
15 Posts
Discussion Starter #1
Hello, I'm hoping someone can help me out. What is this thing? It came in the box of parts I received with the bike and one end appears to screw into the air box, the other end I cannot for the life of me figure out where it attaches. It seems like it might control the flap inside the air box and I guessed it might hook to the throttle cable somehow but I don't see it. I have the manual and it shows it inside the air box but not where it connects to. If you do know where is goes a picture would be perfect if possible. The bike is going to get disassembled so its not a real big deal at the moment, only trying to figure out where everything goes that's already been removed.
Thank you all
Jim
106540
 

·
Premium Member
Joined
·
930 Posts
My gut feeling is that it is the cable that operates the servo control (exhaust flap) on the later model bikes. I have noticed this on my 929 as pictured:
106541
 

·
President: Team Full Chat
Joined
·
7,352 Posts
My gut feeling is that it is the cable that operates the servo control (exhaust flap) on the later model bikes. I have noticed this on my 929 as pictured:
View attachment 106541
DUH! 🤦‍♂️ He"s got the 954. So quickly I forget. Good call there Nigel.
 

·
Registered
Joined
·
3,551 Posts
can confirm. its the flapper cable airbox flapper to servo, which would have been mounted on the left frame under the tank.

i removed mine, along with the flapper and servo motor when the servo failed at 11,000 miles i think. put a servo buddy in place and pinned the htev at its mid point.
 

·
Registered
Joined
·
15 Posts
Discussion Starter #7
Hello,
Thanks everyone for the information. I see where it goes now from your guy's help. The servo motor is still in place, not sure why the guy took it off. O'well, will find out in time.
Jim
 

·
Registered
Joined
·
3,551 Posts
Hello,
Thanks everyone for the information. I see where it goes now from your guy's help. The servo motor is still in place, not sure why the guy took it off. O'well, will find out in time.
Jim
the servo is likely faulty. like i said, it went out on my 954 with 11 thousand miles on the clocks. inside the servo box is a set of cheap plastic gears that strip out easily. you can pull the servo off and split its case. when i took mine apart, about 30 sheared off gear teeth fell out. :)

if your bike isnt throwing the fi code, it may not be damaged. or, the po might have already installed a "servo buddy" that plugs into the main wiring harness and tricks the system into thinking a functioning servo is in place.

some people simply remove the flapper and/or the htev because ultimately, they are more noise pollution control than anything. the bike doesnt make any more or less horsepower/torque with the system, or without it. the induction noise is more badass without it! :)

honda billed the system as a way to increase low end torque, but thats not to say produce more*. by limiting the intake with the flap and varying the htev valve, it increased back pressure on the exhaust. that can move the peak of the torque curve to a lower rpm range. then, at higher rpm's it opens the flap and the htev valve which again increases the torque curve to a higher rpm range.

at least thats what honda sold the concept as.

however, many people speculate the whole system was nothing more than an afterthought put on the bike to control noise pollution in an increasingly emissions conscience world market.

like i said, the system doesnt actually give the bike any extra* torque or horsepower.

but it does quieten the induction noise and exhaust note at anything but wide open high rpm revs.

the kicker is the system is built on the poor durability of that servo motor. its really not a question of "if" the servo will fail, but "when."

mine failed at only 11 thousand miles on a very well looked after indoor stored machine.

so like myself, when faced with buying a new servo that costs hundreds of dollars for it to fail again in short order, people simply eliminate the whole pile of junk. buy a servo buddy(50$) and be done with it.

the system has three position.

when you start the bike the flap closes and the htev valve moves to its most restrictive position.

as soon as the bike moves over 3,000 rpm(i think) the flap and htev opens to their middle positions. they never return to the closed position again until next start up.

finally, when the bike gets over, i wanna say 9,000rmp, its been awhile since i researched the specifics, it opens the flap and htev fully. when it drops below, they return to the midpoint.

obviously, the fully closed position is useless for riding.

so when removing the system people just remove the flap all together and plug the hole in the airbox, where that cable exits.

then use wire or an aftermarket baffle to pin the htev valve on the exhaust in one of two positions. half open, or fully open.

i test rode the bike in both and i couldnt really tell any major difference. i pinned my htev valve in the mid position with the logic: that position adds a little back pressure, giving the torque curve its peak in the midrange of the rpm's. which is where i spend 90% of my time riding.
 

·
Premium Member
Joined
·
930 Posts
Great info, Kevin, cheers.

I don't have my 929 and 954 out very often, so I've never considered this mod as most owners do. I accept your point though that when it does go, to install servo buddy rather than frig around with the original part.
 
1 - 9 of 9 Posts
Top